Not Applicable.
Not Applicable.
1. Field of the Invention
The present invention relates to a self-winding watch comprising a self-winding mass, a ball bearing in order to make this self-winding mass pivot about an axis of the watch""s frame, a reduction gear train for connecting this self-winding mass to a barrel arbor and a reversing mechanism, in order to convert the two-directional rotational movement of said self-winding mass into a one-directional rotational movement, transmitted to said barrel arbor.
2. Description of the Prior Art
Most self-winding mechanisms are provided with a reversing mechanism in order to allow the barrel arbor, integral with the internal end of the barrel spring, to rotate in the direction of loading of this spring, whatever the direction of rotation of the self-winding mass. Without such a reversing mechanism, half of the angular movements of the self-winding mass are in fact lost, therefore requiring twice the movement of the self-winding mass for the same degree of loading of the barrel spring.
The problem posed by reversing mechanisms is that of size, both in terms of area and in terms of height, whatever the system chosen. It is quite obvious that this problem is all the more difficult to solve the smaller the diameter of the movement. When the reversing mechanism is located at the start of the kinematic chain connecting the self-winding mass to the barrel arbor, there is also the problem of an accumulation of mounted devices pivoting about the central axis of the movement and therefore an increase in the thickness of the latter. This problem is also all the more irksome the smaller the diameter of the movement.
A typical example of this accumulation of moving parts at the center of the movement is illustrated, for example, in CH-363,298 in which, in addition to the indicating wheelwork of the watch necessarily placed at the center of the movement, a bridge has to be added for fastening the pivot pin for the self-winding mass, the plate of this self-winding mass mounted so as to pivot on this pin, and two reversers between this bridge and this self-winding mass plate, the system for unidirectionally driving each of these reversers, as well as the spaces necessary between these various superposed elements in order to allow them to rotate about this same pivot pin.
Among the many solutions proposed for solving the space problems, it has already been disclosed, in CH-329,448, to use the self-winding mass to house the reversing mechanism therein. The drawback of such a solution is that it reduces the inertia of this mass, since it is necessary to hollow it out in order to house therein this mechanism which includes a large proportion of empty space. Consequently, the torque which may be transferred to the barrel spring in order to load it is reduced.
According to other solutions, (CH-308,939 and CH-308,940), the reversing mechanism is mounted coaxially on the barrel arbor. Now, the volume that can thus be subtracted from the barrel in order to house the drive spring therein, reduces the energy capable of being stored in the latter.
The object of the present invention is to remedy, at least partly, the various drawbacks mentioned above, especially by reducing the size of the self-winding mechanism and by allowing a more rational use of the space, particularly at the center of the movement.
For this purpose, the subject of the invention is a self-winding watch as disclosed herein.
One of the main advantages of this invention consists in using a large-diameter ball bearing, making it possible to leave a substantial volume at the center of the movement for housing the reversing mechanism. The space saved at the center of the movement does not require the height of the movement to be increased since the raceways of the ball bearing, serving for pivoting the self-winding mass on the frame of the watch, surround the reversing mechanism and therefore can be located naturally at the same level as the latter. This arrangement therefore allows space to be saved in the height direction, since it avoids the abovementioned superposition.
By virtue of this arrangement, the central part of the watch""s frame is no longer occupied by the pivoting members of the self-winding mass, which are moved away toward the outside, although its pivot axis coincides with the center of the movement and although the diameter of this mass therefore remains maximum. The pinions of the reversing mechanism, and therefore those which drive the reduction wheelwork may consequently have a small diameter, given that the central part of the movement is thus freed and that these pinions lie on the inside and no longer on the outside of the ball bearing. The fact of having small-diameter drive pinions for the reduction wheelwork makes it possible to reduce the number of moving parts of the reduction gear train, given that these pinions already constitute a first reduction stage. The fact that the reversers are fastened to the oscillating mass also makes it possible to limit the dead zone, during reversal in the direction of rotation of the self-winding mass, to that of the reversing pinions.
Thanks to the central position of the double reverser and to the small diameter of the drive pinions which are fastened to them, the reduction wheelwork may also occupy a position grouped relatively around the center of the movement and thus can leave the periphery free for the self-winding mass. The torque which can be transferred by the latter depends in fact on its inertia and, consequently, on the mass which is placed far from its pivot pin.
The present invention therefore makes it possible to save space also in the plane, thanks to the grouping of the wheelwork at the center and to the smaller number of moving parts of the reduction wheelwork.